The accurate reproduction of a precise hysteretic characteristic when using integrated circuits has been difficult to achieve in previous encoders because of the difficulty in accurately repeating the exact characteristics of junctions and resistors in integrated circuits. To overcome this problem, the described encoder incorporates a hysteretic circuit in which the hysteretic characteristic is determined by the ratio of two resistors rather than by their absolute values. Since the ratio between resistors on an integrated circuit can be accurately controlled, a repeatable hysteretic integrated circuit having a precise hysteretic characteristic is obtained.